Apparatus and method for extending door brake lifespan

ABSTRACT

The present disclosure includes a retrofitted door brake cam. The retrofitted door brake cam may, in various embodiments, comprise a hub comprising a cylindrical central axle, a plurality of projections extending radially away from an outer circumference of the central axle, and/or a cam comprising a plurality of pins that hold the projections away from a channel wall of a brake housing. The pins may be configured to break away from the cam to release the projections into contact with the channel wall, and the pins may be fitted with a cover, such that the pins are capable of withstanding abrasion and wear. The cover may comprise a cylinder having an axially running aperture, and/or a beveled edge that shaves a layer of the outer surface from one of the plurality of pins as it is fitted over the pin.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priority toU.S. patent application Ser. No. 15/165,549 entitled “APPARATUS ANDMETHOD FOR EXTENDING DOOR BRAKE LIFESPAN” which was filed May 26, 2016.The '549 Application is a continuation of and claims priority to U.S.patent application Ser. No. 14/954,277 entitled “APPARATUS AND METHODFOR EXTENDING DOOR BRAKE LIFESPAN” which was filed Nov. 30, 2015. The'277 Application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/012,860, entitled “APPARATUS AND METHOD FOREXTENDING DOOR BRAKE LIFESPAN,” which was filed Aug. 28, 2013, now U.S.Pat. No. 9,228,385, issued Jan. 5, 2016. The aforementioned applicationsare hereby incorporated by reference herein in their entirety.

BACKGROUND Field

The present disclosure generally relates to door brakes, and moreparticularly to door brakes for rolling doors.

Discussion of the Related Art

Rollup, or rolling, doors are widely used for industrial and commercialpurposes. For example, rollup doors are commonly used as cargo baydoors, self-storage unit doors, garage doors, and the like. Rollup doorsoften comprise a number of interconnected leaves or slats, and thisgroup of interconnected slats may comprise a “door curtain” or“curtain.” The curtain may be mounted to an overhead shaft, and as therollup door is opened, or rolled up, the curtain may wind in layersabout the shaft.

Doors of this type are very heavy and produce considerable vibration asthey open and close. Thus, rollup doors often include a brake (coupledto the shaft) to stop their descent, should they begin to fall ordescend too rapidly.

Many door brakes include a cam coupled to a central hub, where thecentral hub is coupled, in turn, to the overhead shaft around which arollup door may wind and unwind. The hub may comprise a plurality ofmetal projections that, during normal operation, do not engage a brakehousing. Rather, the projections, as they rotate with the hub, areretained away from the brake housing by a plurality of pins extendingfrom an inner (to the brake) surface of the cam. In the event that thedoor to which the brake is coupled falls, the pins are configured tobreak away from the cam, releasing the projections, such that contact ismade between the projections and the brake housing. As this occurs, thehub is no longer able to rotate, and the motion of the door is halted.

However, it is not uncommon that, over the life of the brake, the pinswill slowly abrade away through the vibration induced by the motion ofthe rollup door. As the pins are slowly worn away, the projectionscoupled to the hub make their way ever closer to the brake housing untilcontact is eventually made, bit by bit, with the brake housing. Ascontact is slowly made between the rotating projections and the brakehousing, the projections begin to lathe or mill away that portion of thebrake housing they are intended to contact in the event that a door mayfall. Finally, in the event that the door in fact falls, as what remainsof the pins breaks away, the projections have worn the housing away andare unable to engage, allowing the door to fall. This occurrence is ofparticular concern where brakes are coupled to high cycle rollup doors.

Accordingly, it is desirable to construct a brake capable of safelyoperating over a large number of cycles. In particular, it is desirableto construct a brake in which the pins extending from the cam do notslowly wear away.

SUMMARY

The present disclosure includes a retrofitted door brake. Theretrofitted door brake may, in various embodiments, comprise a hubcomprising a cylindrical central axle, a plurality of projectionsextending radially away from an outer circumference of the central axle,and/or a cam comprising a plurality of pins that hold the projectionsaway from a channel wall of a brake housing. The pins may be configuredto break away from the cam to release the projections into contact withthe channel wall, and the pins may be fitted with a cover, such that thepins are capable of withstanding abrasion and wear. The cover maycomprise a cylinder having an axially running aperture, and/or a bevelededge that shaves a layer of the outer surface from one of the pluralityof pins as it is fitted over the pin. The cover may expand radially asthe beveled edge shaves a layer of the outer surface from the one of theplurality of pins. In addition, the cover may comprise a wear resistantmaterial, and may fit over a portion of a pin, leaving a portion of thepin exposed.

The present disclosure further includes a door brake cam. The cam maycomprise a cylindrical inner surface, an outer surface comprising and agenerally uneven surface that follows the curvature of the cylindricalinner surface. In various embodiments, the inner surface and the outersurface may define an aperture, as well as, about the aperture, a cambody. The cam may further comprise at least one pin extending axiallyaway from the cam body, and the pin may be fitted with a wear resistantcover. The cover may comprise a cylinder having an axially runningaperture and/or at least one beveled edge. The beveled edge may shave alayer of the outer surface from one of the plurality of pins as it isfitted over the pin, and may expand radially as it does so. The covermay comprise a steel cover. In addition, in various embodiments, thewear resistant cover may fit over a portion of a pin, leaving a portionof the pin exposed.

The present disclosure further includes a door brake. The door brake maycomprise a hub comprising a cylindrical central axle, a plurality ofprojections extending radially away from an outer circumference of thecentral axle, and a cam comprising a plurality of wear resistant pinsthat hold the projections away from a channel wall of a brake housing,where the pins configured to break away from the cam to release theprojections into contact with the channel wall. The plurality of pinsmay comprise a wear resistant material, such as steel.

The present disclosure further includes a method for retrofitting a doorbrake. The method may comprise removing a cam from a door brake housing,fitting a cover over at least one pin extending axially from the cam,and replacing the cam within the door brake housing. The cover maycomprise a cylinder having an axially running aperture and/or at leastone beveled edge.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present disclosure will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, wherein:

FIG. 1 illustrates a perspective view of a door brake;

FIG. 2 illustrates exploded view of a door brake, showing the placementof the cam relative to the hub;

FIG. 3 illustrates a perspective view of a door brake with the camremoved;

FIG. 4 illustrates a side perspective view of a cam;

FIG. 5 illustrates a pin cover; and

FIG. 6 illustrates a top perspective view of a cam.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Persons skilled in the art will readily appreciate that various aspectsof the present disclosure may be realized by any number of methods andapparatuses configured to perform the intended functions. Stateddifferently, other methods and apparatuses may be incorporated herein toperform the intended functions. It should also be noted that theaccompanying drawing figures referred to herein are not all drawn toscale, but may be exaggerated to illustrate various aspects of thepresent disclosure, and in that regard, the drawing figures should notbe construed as limiting. Finally, although the present disclosure maybe described in connection with various principles and beliefs, thepresent disclosure should not be bound by theory.

While the specific embodiments are described in greater detail below, ingeneral, the present disclosure will focus primarily upon an apparatusand method for extending the functional lifespan of a door brake.

A door brake may comprise a cam coupled to a central rotating hub. Thecam and hub may be disposed within a housing. The hub may comprise acentral axle and a plurality of angled projections extending therefromthat rotate with the axle. The cam may comprise a plurality of pinsextending away from the cam toward the hub. Specifically, the pins mayextend into the space between the axle and the projections forming thehub. In addition, the cam may be coupled to the hub through one or moresprings. The force exerted by the springs on the cam may cause the pinsextending from the cam to exert a force against the projectionsextending from the hub. This force against the projections may retainthe projections away from the housing. Thus, in other words, duringnormal operation, the pins may hold the projections away from thehousing.

The cam may rotate with the hub as a door shaft to which the hub iscoupled is opened and closed (i.e., lowered and raised). The cam may, inaddition to the features described above, also comprise a series ofpeaks and valleys. And, in various embodiments, an arm coupled to thehousing and terminating in a wheel may follow or roll over the unevensurface of the cam as the cam rotates. Specifically, the brake may besituated such that the force of gravity causes the wheel to drop intoeach consecutive trough as the cam rotates.

The cam may interface with the hub such that, in the event that a doorto which the brake is coupled descends too rapidly or begins to fall,the wheel coupled to the arm may not have sufficient time to drop intothe next consecutive trough. Thus, where a door descends too rapidly,the arm may ride from peak to peak in a raised position. This conditionmay cause a spur disposed at an end of the arm opposite the wheel tocatch in a cam trough. As the spur catches in a cam trough, the wheelmay come to a full stop. However, the hub may continue to rotate, evenas the cam has come to a complete stop. As the hub rotates, however, theprojections extending away from the hub axle may sever or break each pinaway from the cam. As this occurs, the projections, formerly securedaway from the housing by the cam pins, may release into contact with thehousing. And, as the projections make contact with the housing, eachprojection may bite or dig into the housing, causing the hub to stoprotating, and the door, in turn, to stop descending.

In various embodiments, however, the motion of a rollup door(particularly where the door comprises a plurality of metal slats) mayinduce vibration in the brake. Over time, the vibration induced in thebrake may cause the pins extending from the cam to wear or abrade awayas they chatter against the projections outspread from the hub. As thepins wear slowly away, the projections may, likewise, slowly creeptoward the brake housing until they finally begin by a slow process ofabrasion themselves to wear a channel or groove in the brake housing.Finally, if the pins have worn too much away, a brake may not be able tostop a falling door, though the projections may come into some slightcontact with the brake housing. Rather, the channel worn in the housingmay prevent the projections from making contact with the housingadequate to halt the progress of the door.

To extend the functional lifespan of a door brake, then, and asdescribed in greater detail below, one or more pins may be covered witha durable or reinforcing sleeve. The sleeve may comprise a beveled orsharpened edge or edges. In addition, a sleeve may comprise a cylinderhaving an axially running opening or aperture.

In operation, a sleeve may be fitted over a pin such that a beveled edgeof the sleeve shaves off a layer of the outer surface of the pin. Thislayer of material may bunch under the sleeve, causing the sleeve toexpand or distend slightly. The axially running aperture may accommodatethis slight expansion, and the sleeve may thus be tightly pressurefitted over a pin.

With reference now to FIG. 1, a door brake 100 is shown. The brake 100may comprise a cam 102, a hub 104, a housing 106, an arm 108, andsprings 122 a and/or 122 b. The hub 104 may define a generallycylindrical aperture 110, which may pass entirely through the door brake100, and which may couple, during operation, to a rollup door shaft. Asshown, the line passing through the hub 104 may define an axis, denotedA-A′.

The cam 102 may, as shown with respect to FIG. 1 (but see FIG. 4 andsurrounding discussion), comprise an undulating series of crests (e.g.,crest 112) and troughs (e.g., trough 114). The arm 108 may, in turn,comprise a wheel 116, a spur 118, and a pivot 120. The wheel 116 may becapable of spinning. The arm 108 may be capable of pivoting about thepivot 120, such that the arm 108 may move relative to the cam 102.

Referring to FIG. 2, the cam 102 may be removed from the door brake 100to reveal the hub 104 in greater detail. For example, with reference toFIG. 3 (where the cam 102 has been removed), the hub 104 may comprise anaxle 302 and one or more projections (e.g., projection 304). Theprojections 304 may extend radially outward from an outer surface orcircumference of the central axle 302. The projections 304 may becapable of changing position. For example, the projections 304 may, invarious embodiments, be movable between a position that is not incontact with a channel wall 310 formed in the housing 106 and a positionthat is in contact with the channel wall 310 formed in the housing. Thedistance between the projections 304 and the channel wall 310 may beapproximately several millimeters, where contact is not made between theprojections 304 and the channel wall 310.

The projections 304 may further have angled edges 306, as shown. Invarious embodiments, during operation, the hub 104 may rotate in aclockwise direction. Thus, the point 308 of each edge 306 may, ifcontact is made between the edge point 308 and the channel wall 310,oppose continuing rotation of the hub 104. Specifically, if contact ismade between an edge point 308 and the channel wall 310, the edge point308 may burrow into or wedge against the channel wall 310. Thus, in theevent that the projections 304 make contact with the channel wall 310 ofthe housing 106, the projections 304 may halt or substantially halt therotation of the hub 104.

With reference to FIG. 4, as best shown from this perspective (but seecam discussion surrounding FIG. 1 above), the cam 102 may generallycomprise a cylindrical inner surface 404 and an outer surface 406. Theouter surface 406 may comprise a generally uneven surface that followsthe curvature of the cylindrical inner surface 404. Further, the innersurface 404 and the outer surface 406 may define an aperture 408, aswell as, about the aperture 408, the cam 102 (or “cam body” 102). Thecam 102 may, in addition, include at least one pin 402 extending axiallyaway from the cam therefrom, and the pin 402 may be fitted with a wearresistant cover 410.

With additional regard to FIG. 4, a cam 102 may comprise a series ofpins (e.g., pin 402). These pins 402 may extend towards the projections304 described above. Specifically, these pins 402 may extend along theaxis A-A′ in the direction of A′. The pins 402 may comprise a plastic orother similar material, and may, through a force exerted against the cam102 and/or the hub 104, urge the projections 304 into a position that isaway from or not in contact with the channel wall 310. Note, however,that to urge the projections 304 away from the channel wall 310, thepins 402 must remain in contact with the projections 304. Thus, as thehub 104 and cam 102 rotate with the operation of a rolling door, thepins 402 may, through contact with the projections 304, prevent theprojections 304 from halting the operation of the rolling door.

With returning reference now to FIG. 1, as a door shaft coupled to thehub 104 through aperture 110 rotates (i.e., as a door coupled to theshaft is raised and lowered), the hub 104 may rotate in unison. As thehub 104 rotates, the cam 102 may also rotate. And, as the cam 102rotates, the wheel 116 coupled to the arm 108 may roll over the unevensurface or circumference of the cam 102. In particular, the brake may besituated or installed such that the rotation of the cam 102 causes thewheel to rise over a crest 112, while the force of gravity causes thewheel 116 to drop into each consecutive trough 114.

In the event, however, that a door to which the brake 100 is coupleddescends too rapidly or begins to fall, the wheel 116 coupled to the arm108 may not have sufficient time to drop into the next consecutivetrough. Thus, where a door descends too rapidly, the arm 108 may ride orbounce from crest to crest in a raised position. This condition maycause the spur 118 to catch in a cam trough (e.g., trough 114). As thespur 118 catches in a cam trough, the wheel 116 may come to a full stop.However, the hub 104 may continue to rotate, even as the cam 102 hascome to a stop. As the hub 104 rotates, the projections (e.g.,projection 304) extending away from the hub axle 302 may rotate with thehub axle 302 to break one or more pins 402 away from the cam 102. Asthis occurs, the projections 304 (formerly secured away from the channelwall 310 by the pins 402) may be released into a position that makescontact with the channel wall 310. Further, as the projections 304 makecontact with the channel wall 310, each the point 308 of each projection304 may bite or dig into the channel wall 310 of the housing 106,causing the hub 104 to stop rotating, and the door, in turn, to stopdescending.

In various embodiments, however, the motion of a rollup door(particularly where the door comprises a plurality of metal slats) mayinduce vibration in the brake 100. Over time, the vibration induced inthe brake 100 may cause the pins 402 extending from the cam 102 to wearor abrade away as they chatter and vibrate against the projections 304outspread from the hub 104. As the pins 402 wear slowly away, theprojections 304 may, likewise, slowly creep toward the channel wall 310of the brake housing 106 until they finally begin to wear a deeperchannel or groove in the channel wall 310 of the brake housing 106.Further, if the pins 402 have worn too much away, a brake 100 may not beable to stop a falling door. Specifically, if the channel wall 310 isworn too deeply, the projections 304 may come only into slight contactwith channel wall insufficient to halt a falling door, or theprojections 304 may not make contact with the channel wall 310 at all.

To extend the functional lifespan of a door brake 100, as described morebriefly above, one or more pins 402 may be covered with a durable and/orreinforcing sleeve or cover 500. For example, with attention to FIG. 5,a cover 500 may comprise a cylinder having an axially running opening,slot, or aperture 502. The cover 500 may comprise any of a variety ofsuitable materials, including, for example, steel, hardened steel,various alloys, sintered metals, high performance composites and/orplastics, and the like. In addition, in various embodiments, the cam 102and/or one or more pins (e.g., pin 402) may comprise any of thematerials described herein, including for example, a sintered metal.

In various embodiments, a cover 500 may be coupled to each pin (e.g.,pin 402). More particularly, a cover 500 may be fitted over (e.g.,pressure fitted over) a pin. To this end, a cover 500 may comprise abeveled edge 504. In addition, a cover may comprise greater than asingle beveled edge, so that a cover may be fitted over a pin fromeither of its ends. Further, in various embodiments, a cover 500 maycover an entire length of a pin 402, and/or the cover may leave aportion of the pin 402 (e.g., the portion of the pin 402 closest to thecam 102) uncovered, so that the pin 402 may more easily break away fromthe cam 102 (see, e.g., FIG. 4).

In operation, as the cover 500 is fitted over a pin, the beveled edge504 may shave or shear off a portion or layer of the outer (usuallyplastic) surface of the pin. This layer of material may bunch under thecover 500, causing the cover 500 to undergo a radial expansion ordistension, thereby tightening the cover 500 further about the pin. Theaxially running aperture 502 may accommodate or permit this expansion ofthe cover 500. The cover 500 may thus be tightly pressure fitted over apin. Therefore, as shown briefly with respect to FIG. 6, the pins 602a-f may be coupled to covers 604 a-f. Further, in various embodiments, apin 402 not be fitted with a reinforcing cover 500. Rather, the pin 402may comprise a hardened material from the first. That is, a pin 402 maybe manufactured to include a wear resistant material, such as a metal,and/or a pin 402 may be manufactured that that it wholly comprises awear resistant material.

The present disclosure therefore permits a relatively low cycle doorbrake to be coupled to an extremely high cycle rolling door system. Thepresent disclosure further permits the installation of a (retrofitted)relatively low cycle door brake to a plurality of low cycle doors.Specifically, as low cycle doors wear out and require replacement, theretrofitted (or newly constructed) brake disclosed herein may be coupledto each successive low cycle door system. In addition, the presentdisclosure contemplates the construction of high cycle door brakeshaving wear resistant pins capable of withstanding the damage andabrasion inherent to long life operation. In tests, one particular lowcycle brake was in need of replacement due to pin wear afterapproximately 200,000 cycles. This brake was retrofitted as describedherein with a plurality of pin covers, and the brake's functionallifespan was increased to over 650,000 cycles. Thus, the features andadvantages of the present disclosure have proven quite useful in thefield.

Numerous characteristics and advantages have been set forth in thepreceding description, including various alternatives together withdetails of the structure and function of the devices and/or methods. Thedisclosure is intended as illustrative only and as such is not intendedto be exhaustive. It will be evident to those skilled in the art thatvarious modifications may be made, especially in matters of structure,materials, elements, components, shape, size, and arrangement of partsincluding combinations within the principles of the invention, to thefull extent indicated by the broad, general meaning of the terms inwhich the appended claims are expressed. To the extent that thesevarious modifications do not depart from the spirit and scope of theappended claims, they are intended to be encompassed therein.

What is claimed is:
 1. A door brake cam comprising: a cylindrical innersurface; an outer surface comprising a generally uneven surface thatfollows a curvature of the cylindrical inner surface, the inner surfaceand the outer surface defining an aperture, the inner surface and theouter surface further defining, about the aperture, a cam body; a firstpin extending axially away from the cam body and fitted with a firstwear resistant cover; and a second pin extending axially away from thecam body and fitted with a second wear resistant cover.
 2. The doorbrake cam of claim 1, wherein the first wear resistant cover comprises acylinder having an axially running aperture.
 3. The door brake cam ofclaim 1, wherein the first wear resistant cover comprises at least onebeveled edge.
 4. The door brake cam of claim 3, wherein the beveled edgeof the first wear resistant cover shaves a layer of an outer surface ofthe first pin as it is fitted over the first pin.
 5. The door brake camof claim 4, wherein the first wear resistant cover expands radially asthe beveled edge of the first wear resistant cover shaves a layer of theouter surface from the first pin.
 6. The door brake cam of claim 1,wherein the first wear resistant cover comprises steel.
 7. The doorbrake cam of claim 1, wherein the first wear resistant cover fits over aportion of a pin, leaving a second portion of the first pin exposed. 8.A door brake cam comprising: a cam body defined by an inner surface andan outer surface, wherein the inner surface is substantially circularand the outer surface comprises a plurality of crests separated bytroughs; a plurality of pins extending axially away from the cam body,wherein each of the plurality of pins is fitted with a wear resistantcover.
 9. The door brake cam of claim 8, wherein at least one of thewear resistant covers comprises a cylinder having an axially runningaperture.
 10. The door brake cam of claim 1, wherein at least one of thewear resistant covers comprises at least one beveled edge.
 11. The doorbrake cam of claim 10, wherein the beveled edge of the at least one ofthe wear resistant cover shaves a layer of an outer surface of at leastone of the plurality of pins as it is fitted over the pin.
 12. The doorbrake cam of claim 11, wherein the at least one of the wear resistantcovers expands radially as the beveled edge shaves a layer of the outersurface from the pin.
 13. The door brake cam of claim 12, wherein theouter surface of the pin comprises plastic.
 14. The door brake cam ofclaim 8, wherein at least one of the wear resistant covers comprisessteel.
 15. The door brake cam of claim 8, wherein at least one of thewear resistant covers fits over a portion of at least one of theplurality of pins, leaving a second portion of the pin exposed.